A continuously variable transmission (CVT) is a type of transmission capable of providing more useable power, better fuel economy and a smoother driving experience than a traditional mechanical or automatic transmission. A typical automotive transmission may include a fixed number of gears from which to select. The transmission may employ a gearset that provides a given number of gear ratios. The transmission shifts gears in an attempt to provide the most appropriate gear ratio for a given situation. Switching into a particular gear may allow the vehicle to produce the maximum power it can with the least amount of energy.
A continuously variable transmission (CVT) is a transmission capable of changing seamlessly through an infinite number of effective gear ratios between maximum and minimum values. A CVT makes it possible to vary progressively the transmission ratio. This contrasts with other mechanical transmissions that offer a fixed number of gear ratios. A CVT may provide better fuel economy than other transmissions, by enabling the engine to run at its most efficient revolutions per minute (RPM) for a range of vehicle speeds. A CVT may also be used to maximize the performance of a vehicle by allowing the engine to turn at the RPM at which it produces peak power. This is typically higher than the RPM that achieves peak efficiency. A CVT may create a more fuel efficient vehicle. The nearly unlimited number of positions helps ensure it is always using the appropriate amount of power.
Disclosed herein is a continuously variable drive mechanism that includes an input member rotatable about an input axis of rotation. The input member includes a partial spheroid-shaped input traction surface. The drive mechanism further includes an output member rotatable about an output axis of rotation. The output member includes a partial spheroid-shaped output traction surface. A ring member overlays the input and output members. The ring member is rotatable in a rotational plane and includes a ring traction surface that engages the input traction surface of the input member and the output traction surface of the output member to rotatably couple the input member to the output member.